It is common in the art of making electrical cables and insulated conducting wires to encase the cables or conductors in polymeric insulation material which may be placed around the conductors in semi-liquid (melt) form and heated to vulcanize or cross-link the polymer composition while it is extruded through a die, holding the conductor in the desired position in the die. Or, the polymeric material may be held in a stationary mold for vulcanizing or cross-linking (curing) under the influence of heat and pressure when splicing is performed in place.
The thermosetting materials commonly used for these purposes are well-known to the art, and have been published many times. See, for example, the recipes in Exxon Chemical Co. published product literature "Materials for the Electrical Industry".
However, particularly in the case of cables which must frequently be terminated and/or spliced in place, such as lengthy power cables for minimg machinery, which are frequently broken or severed by the machinery itself, a difficult problem is presented when the insulation is so adherent to the conductor or so deeply impregnated in the interstices of the strands of the cable that it is extremely difficult to expose a clean conductor surface for termination or connecting with another conductor or portion of the same one. To overcome this problem in the past the industry has employed tin-coated conductors, which are known to be readily strippable, but which add a significant expense far out of proportion to the small areas where splicing or termination is performed. A relatively inexpensive freely strippable thermosetting insulation material is difficult to come by in the art.